A large number of measuring chamber units have been used in the past in various electrochemical measuring apparatus. U.S. Pat. No. 4,160,714 describes a single unit measuring chamber used for pH values, gas values and other types are known for use in measuring various analytes including metal ions in body fluids such as blood.
It is known to use reference electrodes and measure electromotive force between a reference electrode and an electrode mounted beneath a membrane over which a fluid is passed to determine the ionic content of the fluid. Ions such as potassium, sodium and others are customarily tested in medical laboratories by such equipment. Conventional electronics, pumping and flow meters and the like are interconnected with units for measuring which units contain measuring chambers and electrodes.